wireless sensor networks are currently one of the hottest research topics of the mobile/wireless community. they combine current research and development trends from a number of different disciplines (hardware design, information/signal processing, communication networks, control theory, databases, etc.) in order to fill up a new space of challenges, distinct from the traditional kinds of networks. while the amount of publications on wsns is vast, there is no single source of information that would make these research fields easily accessible to a graduate student or practitioner. this book aims to close this gap covering: architectures, communication protocols, application support, practical examples & case studies and modeling & simulation. moreover, the book will treat issues relevant to a protocol design practitioner: how to model such systems and how to evaluate the performance using simulations.